Coffee machine

ABSTRACT

A coffee machine ( 10 ) comprises a removable brewing unit ( 18 ), in which ground coffee powder is compacted in a brewing chamber along a main axis of the brewing unit ( 18 ) between a movable lifting bottom and a plunger that can be displaced toward the lifting bottom. Pressurized hot water is pressed through the compacted coffee powder. Afterwards, the lifting bottom and plunger are displaced together along the main axis in order to push the remaining filter cake out of the brewing chamber whereby ejecting it transversal to the main axis. The aim of the invention is to provide a coffee machine of the aforementioned type with a simplified and space-saving design as well as with an easier accessibility for cleaning and maintenance purposes. To these ends, the brewing unit ( 18 ) is designed so that it can be pushed into the coffee machine ( 10 ) from the front towards the back with the main axis parallel to the direction of insertion.

TECHNICAL FIELD

[0001] The present invention relates to the field of automated coffeepreparation. It concerns a coffee machine according to the preamble toclaim 1.

[0002] A coffee machine of this type is known, for example, from thepublication WO-A1-93/19655.

STATE OF THE ART

[0003] With automatic coffee preparation by means of coffee-makingmachines or coffee-vending machines, in which the coffee in bean form isfirst ground in a grinder housed in the machine, the ground coffeepowder is then placed in a brewing chamber and compacted therein,pressurized hot water is then supplied through the brewing chamber and,finally, upon completion of the brewing process, the remaining filtercake is pushed out of the brewing chamber and ejected into a collectingcontainer, it is desirable, in spite of the complex preparation steps tobe performed, to arrange the machine in a manner such that it is ofsimple construction, operates for the longest possible periods of timewithout malfunction or maintenance, and is easy to clean and tomaintain.

[0004] In the publication cited in the introduction, a coffee machine isnow proposed, the central element of which is a removable brewing unit(1 in FIGS. 1-3). A base and a plunger are arranged so as to bedisplaceable along a main axis in this brewing unit and performdifferent movement sequences that are coordinated with one another.These travels are designed in a manner such that ground coffee powderplaced in a filling chamber is transported into an adjacent brewingchamber and is compressed therein between the base and the plunger.Pressurized hot water is then passed through the cylindrical compressedpowder in a radial direction. The brewed coffee produced is outlet fromthe brewing chamber radially and discharged downwards. Upon completionof the brewing process, the remaining filter cake is pushed out of thebrewing chamber in an axial direction and is ejected transverselyrelative to the main axis by means of an ejector. The different travelsof the base, of the plunger, and of the ejector are brought about by acommon drive unit by means of a special mechanism which includes,amongst other things, two parallel racks engaged by a pinion. For adetailed explanation of the operation, reference should be made to thepublication cited.

[0005] As can be seen from FIGS. 1 and 4 of the publication and from thedescription on page 4, last paragraph, the brewing unit is installedwith its main axis, which corresponds to the direction of movement ofthe plunger, arranged transversely in the coffee machine, that is, themain axis extends parallel to the front of the machine. However, thisarrangement has various disadvantages: owing to the displaceablearrangement of the base and of the plunger, as well as to thearrangement of the filling chamber, the brewing chamber, and theejection region longitudinally relative to the main axis, the brewingunit reaches a relatively great length in the direction of the mainaxis, which length is effective as a width in the transverseinstallation described. Since, as well as the brewing unit, furtherfunctional units such as grinder, drive unit, water-heating unit, waterreservoir, filter-cake collecting container, control electronics etc.are housed in the machine and must—at least partially—also be asaccessible as possible from the front, the machine as a whole has acomparatively large width which is not always desirable.

[0006] Basically, it would be possible to design the transverselyinstalled brewing unit so that it could be pushed in from the side.However, in practice, this would mean that sufficient space would alwayshave to remain clear beside the machine to permit unobstructed insertionor removal of the brewing unit. It is therefore usual to insert thetransversely installed brewing unit directly transversely from the frontand to remove it towards the front. However, the space in front of thebrewing unit in the machine must consequently be kept free over theentire width of the brewing unit.

[0007] A further problem arises in the coupling of the brewing unit,which has been removed and reinserted (for example, after cleaning), tothe drive unit, which remains in the machine. In fact if, uponinsertion, the movable elements (base, plunger, etc.) of the brewingunit adopt positions other than those adopted upon removal, theengagement point for the coupling is also displaced. An adjustment ofthe drive unit to the new engagement point, however, is difficult withthe transverse installation of the brewing unit.

[0008] Disadvantages owing to the transverse installation also arisewith regard to the water supply: in order to limit, as far as possible,cooling of the brewed coffee on the path from the brewing chamber to theoutlet, this path must be kept as short as possible. However, this meansa radial flow through the brewing chamber which results in comparativelyhigh flow resistances.

STATEMENT OF THE INVENTION

[0009] The object of the invention is therefore to provide anautomatically operating coffee machine which has a compact brewing unitand which overcomes the disadvantages of known coffee machines and ischaracterized in particular by a simplified and space-saving design aswell as easier accessibility for cleaning and maintenance purposes.

[0010] The object is achieved by the features of claim 1, taken as awhole. The essence of the invention is to design the brewing unit sothat it can be pushed into the coffee machine from the front towards therear with the main axis parallel to the direction of insertion. Thebrewing unit thereby requires only a small width of the machine bothinside the machine and also during installation and removal. Moreover,this longitudinal insertion permits the arrangement under the brewingunit of suitable collecting containers which extend along the entirelength of the brewing unit and thus offer protection against leakages inthe brewing unit.

[0011] A first preferred embodiment of the invention is characterized inthat one or a plurality of guides, which extend parallel to the mainaxis of the brewing unit and are preferably bar-shaped, are provided forguiding the brewing unit during insertion in and removal from the coffeemachine, and in that a catch is provided at the front end of the guide,for locking the inserted brewing unit. The guide facilitates theaccurately positioned insertion of the brewing unit and thus ensures ina simple manner the mechanical and hydraulic connections between thebrewing unit and the machine that are necessary for correct operation.

[0012] A second preferred embodiment of the coffee machine according tothe invention is characterized in that, in the brewing unit, thepressurized hot water is forced through the coffee powder disposed inthe brewing chamber in the direction of the main axis, forwards from therear and leaves through an outlet which is arranged at the front end ofthe brewing unit and is preferably adjustable in height, and in that themovable base and the plunger are equipped, on their surfaces facing thebrewing chamber, with respective mesh plates through which the hot waterenters the brewing chamber and the brewed coffee leaves the brewingchamber, respectively. With the longitudinal configuration of thebrewing unit according to the invention, with improved flow through thecoffee powder, this enables advantageously short paths for the fluid tobe achieved, which is of benefit to the quality of the brewed coffee.

[0013] Another preferred embodiment of the invention is characterized inthat the movable base and the plunger are driven by means of anactuating slide which is arranged so as to be displaceable in thedirection of the main axis in the brewing unit and which is releasablyin engagement with a driving dog which is situated on a threaded rodarranged parallel to the main axis and which can be displaced along themain axis by rotation of the threaded rod, and in that releasableengagement between the driving dog and the actuating slide is broughtabout by a latching hook which extends in the direction of the main axisand is arranged so as to be pivotable on the driving dog about a pivotaxis arranged transversely relative to the main axis. The engagementbetween the driven dog and the inserted brewing unit can bere-established easily and automatically thereby, even if the engagementposition has changed in the meantime.

[0014] Particularly simple control of the compacting of the coffeepowder can be achieved if, in addition, the threaded rod is mounted soas to be displaceable in the direction of the main axis against thepressure of a spring element, preferably a spring assembly, and if thedisplacement of the threaded rod against the pressure of the springelement or spring assembly, for a predetermined travel as established bythe striking of the driving dog, of the actuating slide, or of theplunger, against a resistance, is used for the control or switching ofthe drive.

[0015] The change in density arising in the moistened coffee powder canbe compensated for and an optimal brewing process can thereby be ensuredif the plunger is moved by means of a plunger actuator displaceable inthe direction of the main axis and if the plunger is operativelyconnected to the plunger actuator by means of compression springs actingin the direction of the main axis.

[0016] Preferably, the pressurized hot water is supplied into thebrewing chamber through the plunger and a valve mechanism is arranged onthe plunger, the valve mechanism being closed when the plunger presseson the coffee powder disposed in the brewing chamber with apredetermined pressure and relieving the pressure of the pressurizedwater and allowing the water to escape to the exterior when the pressureof the plunger on the coffee powder is removed. In particular, this isbrought about by virtue of the fact that the valve mechanism includesvalve push-rods which are arranged on the plunger actuator and which,upon sufficient compression of the compression springs, sealingly entercorresponding valve bores in the plunger, which valve bores are incommunication with a hot-water supply duct. Preferably, the hot-watersupply duct can extend directly through one of the valve push-rods andthe valve bores can be in communication with the brewing chamber througha mesh plate.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The invention will be described in greater detail below by meansof embodiments, with reference to the drawings. In the drawings:

[0018]FIG. 1 is an overall view from the front of a coffee machineaccording to a preferred embodiment of the invention in the closedcondition,

[0019]FIG. 2 is a cross-section through the machine of FIG. 1 in theplane II-II,

[0020]FIG. 3 is a vertical longitudinal section through the brewing unitof the machine of FIG. 2,

[0021]FIG. 4 is a horizontal longitudinal section through the brewingunit of the machine of FIG. 2,

[0022]FIG. 5 is a perspective view of the plunger of FIG. 4, viewed fromthe rear and from the front,

[0023]FIG. 6 is a longitudinal section through the plunger of FIG. 5 ina plane extending through the valve bores, and

[0024]FIG. 7 is a longitudinal section through the plunger of FIG. 5 ina plane extending through the spring pins.

IMPLEMENTATION OF THE INVENTION

[0025] In FIG. 1, a coffee machine according to a preferred embodimentof the invention is shown in the closed condition, in an overall viewfrom the front. FIG. 2 shows a cross-section through the machine of FIG.1 in the plane II-II. The coffee machine 10 has, at the top, a loadinghopper 11 for the coffee beans to be ground. An associated grinder 24 isarranged beneath the loading hopper 11. The coffee ground in the grinder24 falls into a compact brewing unit 18 and is compacted therein in abrewing chamber (29 in FIGS. 3, 4). Pressurized hot water is then forcedthrough the compressed powder. The resulting brewed coffee leaves thebrewing chamber through a spring-loaded creaming valve and is drawn offthrough an outlet 15 which projects forwards out of the coffee machine10 and is preferably adjustable in height (pivotable), for example, intoa cup which stands on a support surface 14 arranged beneath the outlet15. A steam/hot water nozzle 16 is arranged beside the outlet 15 for thefoaming of milk (cappuccino) or for delivering hot water. The removablebrewing unit 18 is covered at the front by a swivelling or removablecover 17. An operating console 12 with the necessary operation andcontrol elements is provided for the operation of the machine. A watercontainer 13 that can be pulled out towards the front is arrangedbeneath the operating console 12, for storing the water supply. Acollecting container 48 for the filter cakes that are produced duringthe brewing process and are ejected from the brewing chamber is disposedon the left, beside the water container 13, directly beneath the brewingunit 18 situated behind the cover 17. The collecting container 48 can bepulled out towards the front by means of a gripping recess 49. Thecollecting container 48 extends, together with an extension 50 formed onthe rear region, beneath the brewing unit 18 along the entire length ofthe brewing unit 18. If any leakages should occur in the brewing unit18, the collecting container 48 can thus also collect dripping water orcoffee slops which can then easily be removed by pulling out thecollecting container 48 together with the collected filter cakes.Permanent soiling of the coffee machine 10 can thus safely be prevented.

[0026] The brewing unit 18 extends, according to FIGS. 3 and 4, along amain axis 48. It includes, in addition to a filling chamber 30 and abrewing chamber 29, a movable base 28 displaceable in the direction ofthe main axis 48 and a plunger 32, also displaceable in the direction ofthe main axis 48. As described in the publication cited in theintroduction, the ground coffee powder falls out of the grinder 24through a filling opening 31 into the filling chamber 30. By adisplacement of the plunger 32 towards the right (FIG. 3), the loadedcoffee powder is pushed from the filling chamber 30 into the brewingchamber 29 where it is pressed against the movable base 28 and therebycompacted. Respective mesh plates 46 and 49 are secured on the endsurfaces of the plunger 32 and of the movable base 28 (FIG. 4). Hotwater is supplied into the brewing chamber 29 through the mesh plate 46from the left, in an axial direction, through the plunger 32. The brewedcoffee leaves the brewing chamber 29 through the mesh plate 47, axiallytowards the right, through the movable base 28, and reaches the directlyadjacent outlet 15 (FIG. 4).

[0027] The brewing unit 18 is pushed into the coffee machine 10 in thelongitudinal direction, that is, in the direction of the main axis 48,from the front towards the rear (FIG. 2). For guiding the brewing unit18 during insertion, use is made of one or a plurality of bar-shapedguide(s) 19 on the front end of which a (releasable) catch 20 for thebrewing unit 18 is also arranged. The movable base 28 and the plunger 32are moved, for example, by a rack mechanism as described by way ofexample in WO-A1-93/19655, of an actuating slide 27 arranged so as to bedisplaceable in the brewing unit 18. The actuating slide 27 can bebrought into engagement, by means of a releasable latching hook 26, witha driving dog 25 which is situated on a rotatable threaded rod 21 whichis driven by means of a drive wheel 22 of a drive motor, not shown. Whenthe brewing unit 18 is pushed into the coffee machine 10, the drivingdog 25 moves towards the right, with the latching hook 26, until thelatching hook 26 has entered the actuating slide 27 and engaged therein.The engagement between the driving dog 25 and the actuating slide 27 canthus always safely be established, irrespective of exactly where theactuating slide 27 is disposed in the brewing unit 18 during insertion.

[0028] The threaded rod 21 is arranged parallel to the guide 19 in thecoffee machine 10, is displaceable axially against the pressure of aspring assembly 23 composed of disc springs, and operates a microswitch(not shown) when the driving dog 25 strikes a resistance. In particularif, owing to compaction of the coffee powder, an opposing force buildsup on the plunger 32 and thereby also on the driving dog 25, themicroswitch is operated when a predetermined value of that opposingforce is exceeded. The compaction process can thus safely be controlled.

[0029] According to a preferred embodiment of the invention, the plunger32 is not coupled rigidly to the drive members but is connected, bymeans of two compression springs 42, 43, to a separate plunger actuator33 which is driven by the actuating slide 27. The compression springs42, 43 are situated with one end on two spring pins 40, 41 (see alsoFIGS. 5 and 7) which are formed on the inner end surface of the plunger32. This spring coupling has a particular advantage: when the (dry)coffee powder is compacted, the drive switches off when a predeterminedpressure is reached and the plunger actuator 33 and the plunger 32 cometo a halt, in the course of which, owing to the prevailing pressure, thecompression springs 42, 43 are compressed to a predetermined extent. Ifthe hot water is now forced through the brewing chamber 29, owing to themoistening of the coffee powder, the density in the powder increases andthe pressure in the powder decreases. The energy stored in thecompression springs 42, 43 then suffices to push the plunger 32 frombehind and to compensate for the loss in volume so that the formation ofundesired water channels past the coffee powder is safely prevented.

[0030] The coupling described between the plunger 32 and the plungeractuator 33 by means of the compression springs 42, 43 permits thesimple construction of a valve mechanism which serves for the saferelief of the pressure from the pressurized water system upon completionof the brewing process. For this purpose, valve bores 44, 45 withparallel axes are provided in the plunger 32 (FIGS. 3, 5 and 6);corresponding valve push-rods 36, 37 arranged on the plunger actuator 33(FIG. 3) enter the valve bores 44, 45 sealingly when the compressionsprings 42, 43 are sufficiently greatly compressed. Sealing takes placeby means of O-rings (not shown) which are inserted in correspondinggrooves 38, 39 on the valve push-rods 36, 37. One of the valvepush-rods, that is the valve push-rod 36, also serves as an (axial)supply duct 34 for the hot water. Moreover, connection to the hot watersystem of the coffee machine 10 is established by means of a fluid-tightplug-type connection 35 which is operated upon the insertion of thebrewing unit 18 in the machine.

[0031] If, upon completion of a brewing process, the plunger actuator 33with the plunger 32 is withdrawn, the compression springs 42, 43 arereleased and the valve push-rods 36, 37 move out of the valve bores 44,45 so that residual pressurized hot water can come out of the supplyduct 34, with pressure relief, into the space between the plungeractuator 33 and the plunger 32, from where it can be discharged to theexterior.

[0032] Legend 10 coffee machine 11 filling hopper 12 operating console13 water container 14 support surface (coffee cup) 15 outlet 16steam/hot water nozzle 17 cover 18 brewing unit (removable) 19 guide(bar-shaped) 20 catch 21 threaded rod 22 drive wheel 23 spring assembly24 grinder 25 driving dog 26 latching hook 27 actuating slide 28 movablebase 29 brewing chamber 30 filling chamber 31 filling opening 32 plunger33 plunger actuator 34 supply duct 35 plug-type connection 36, 37 valvepush-rod 38, 39 groove (for O-ring) 40, 41 spring pin 42, 43 compressionspring 44, 45 valve bore 46, 47 mesh plate (perforated plate) 48collecting container (filter cakes) 49 gripping recess (collectingcontainer) 50 extension (collecting container)

1. Coffee machine (10) including a horizontally removable brewing unit(18) in which ground coffee powder is compacted along a main axis (48)of the brewing unit (18) between a movable base (28) and a plunger (32)that can be displaced towards the movable base (28) in a brewing chamber(29), pressurized hot water is forced through the compacted coffeepowder and, the remaining filter cake is then pushed out of the brewingchamber (29) by displacement of the movable base (28) and of the plunger(32) together along the main axis (48), and is ejected transverselyrelative to the main axis (48), characterized in that the brewing unit(18) is designed so that it can be pushed into the coffee machinehorizontally from the front towards the rear, with the main axis (48)parallel to the direction of insertion.
 2. Coffee machine according toclaim 1, characterized in that, one or a plurality of guides (19) whichextend parallel to the main axis (48) of the brewing unit and arepreferably bar-shaped are provided for guiding the brewing unit (18)during insertion in and removal from the coffee machine (10).
 3. Coffeemachine according to claim 2, characterized in that a catch (20) isprovided at a front end of the guide (19) for locking the insertedbrewing unit (18).
 4. Coffee machine according to any one of claims 1 to3, characterized in that, in the brewing unit (18), the pressurized hotwater is forced through the coffee powder disposed in the brewingchamber (29) in the direction of the main axis (48), forwards from therear and leaves through an outlet (15) which is arranged at a front endof the brewing unit (18) and is preferably adjustable in height. 5.Coffee machine according to claim 4, characterized in that the movablebase (28) and the plunger (32) are equipped, on their surfaces facingthe brewing chamber (29), with respective mesh plates (46, 47) throughwhich the hot water enters the brewing chamber (29) and the brewedcoffee leaves the brewing chamber (29), respectively.
 6. Coffee machineaccording to any one of claims 1 to 5, characterized in that the movablebase (28) and the plunger (32) are driven by means of an actuating slide(28) which is arranged so as to be displaceable in the direction of themain axis (48) in the brewing unit (18) and which is releasably inengagement with a driving dog (25) which is situated on a threaded rodarranged parallel to the main axis (48) and which can be displaced alongthe main axis (48) by rotation of the threaded rod (21).
 7. Coffeemachine according to claim 6, characterized in that the releasableengagement between the driving dog (25) and the actuating slide (27) isbrought about by means of a latching hook (26) which extends in thedirection of the main axis (48) and is arranged so as to be pivotable onthe driving dog (25) about a pivot axis arranged transversely relativeto the main axis (48).
 8. Coffee machine according to any one of claims6 and 7, characterized in that the threaded rod (21) is mounted so as tobe displaceable in the direction of the main axis (48) against thepressure of a spring element, preferably a spring assembly (23), and inthat the displacement of the threaded rod (21) against the pressure ofthe spring element or spring assembly (23) for a predetermined travel,as established by the striking of the driving dog (25), of the actuatingslide (27), or of the plunger (32), against a resistance, is used forthe control or switching of the drive.
 9. Coffee machine according toany one of claims 1 to 8, characterized in that the plunger (32) ismoved by means of a plunger actuator (33) displaceable in the directionof the main axis (48), and in that the plunger (32) is operativelyconnected to the plunger actuator (33) by means of compression springs(42, 43) acting in the direction of the main axis (48).
 10. Coffeemachine according to claim 9, characterized in that the pressurized hotwater is supplied into the brewing chamber (29) through the plunger(32), and in that a valve mechanism (36, 37, 38, 39, 44, 45) is arrangedon the plunger (32), the valve mechanism (36, 37, 38, 39, 44, 45) beingclosed when the plunger (32) presses on the coffee powder disposed inthe brewing chamber with a predetermined pressure, and relieving thepressure of the pressurized water and allowing the water to escape tothe exterior when the pressure of the plunger (32) on the coffee powderis removed.
 11. Coffee machine according to claim 10, characterized inthat the valve mechanism includes valve push-rods (36, 37) which arearranged on the plunger actuator (33) and which, upon sufficientcompression of the compression springs (42, 43), sealingly entercorresponding valve bores (44, 45) in the plunger (32), which valvebores are in communication with a hot-water supply duct (34).
 12. Coffeemachine according to claim 11, characterized in that the hot-watersupply duct (34) extends directly through one of the valve push-rods(36, 37), and in that the valve bores (44, 45) are in communication withthe brewing chamber (29) through a mesh plate (46).